server.js

const express = require('express');
const bodyParser = require('body-parser');
const path = require('path');
const multer = require('multer');
const cloudinary = require('cloudinary');
const PORT = process.env.PORT || 4004;

const storage = multer.diskStorage({
    destination: function (req, file, cb) {
        cb(null, 'uploads/')
    },
    filename: function (req, file, cb) {
        cb(null, file.originalname);
    }
})
const upload = multer({ storage: storage });

const app = express();
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

app.get('/', (req, res) => {
    cloudinary.v2.api.resources((error, result) => {
        let html = '<form method="post" enctype="multipart/form-data">'
          + 'File: <input type="file" name="fileupload" />'
          + '<input type="submit" value="Upload" />'
          + '</form><br><br>'
          + '<h1>Files</h1><ul>';
        for (let i = 0; i < result.resources.length; i += 1) {
            html += '<li><a href="'
              + result.resources[i].secure_url + '">' 
              + result.resources[i].public_id + '</a></li>';
        }
        html += '</ul>';
        res.send(html);
    })
})

app.post('/', upload.single('fileupload'), (req, res) => {
    cloudinary.uploader.upload(req.file.path, (result) => {
        res.send('<h1>Success</h1><a href="/">Home</a>');
    })
})

app.listen(PORT, () => console.log(`App listening on port ${PORT}!`));